/*
 * Copyright (c) 2005, 2006, 2007 Lev Walkin <vlm@lionet.info>.
 * All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#include <asn_system.h>
#include <asn_internal.h>
#include <per_support.h>

char *
per_data_string(asn_per_data_t *pd) {
        static char buf[2][32];
        static int n;
        n = (n+1) % 2;
        snprintf(buf[n], sizeof(buf[n]),
                "{m=%ld span %+ld[%d..%d] (%d)}",
                (long)pd->moved,
                (((long)pd->buffer) & 0xf),
                (int)pd->nboff, (int)pd->nbits,
                (int)(pd->nbits - pd->nboff));
        return buf[n];
}

void
per_get_undo(asn_per_data_t *pd, int nbits) {
        if((ssize_t)pd->nboff < nbits) {
                assert((ssize_t)pd->nboff < nbits);
        } else {
                pd->nboff -= nbits;
                pd->moved -= nbits;
        }
}

/*
 * Extract a small number of bits (<= 31) from the specified PER data pointer.
 */
int32_t
per_get_few_bits(asn_per_data_t *pd, int nbits) {
        size_t off;     /* Next after last bit offset */
        ssize_t nleft;  /* Number of bits left in this stream */
        uint32_t accum;
        const uint8_t *buf;

        if(nbits < 0)
                return -1;

        nleft = pd->nbits - pd->nboff;
        if(nbits > nleft) {
                int32_t tailv, vhead;
                if(!pd->refill || nbits > 31) return -1;
                /* Accumulate unused bytes before refill */
                ASN_DEBUG("Obtain the rest %d bits (want %d)",
                        (int)nleft, (int)nbits);
                tailv = per_get_few_bits(pd, nleft);
                if(tailv < 0) return -1;
                /* Refill (replace pd contents with new data) */
                if(pd->refill(pd))
                        return -1;
                nbits -= nleft;
                vhead = per_get_few_bits(pd, nbits);
                /* Combine the rest of previous pd with the head of new one */
                tailv = (tailv << nbits) | vhead;  /* Could == -1 */
                return tailv;
        }

        /*
         * Normalize position indicator.
         */
        if(pd->nboff >= 8) {
                pd->buffer += (pd->nboff >> 3);
                pd->nbits  -= (pd->nboff & ~0x07);
                pd->nboff  &= 0x07;
        }
        pd->moved += nbits;
        pd->nboff += nbits;
        off = pd->nboff;
        buf = pd->buffer;

        /*
         * Extract specified number of bits.
         */
        if(off <= 8)
                accum = nbits ? (buf[0]) >> (8 - off) : 0;
        else if(off <= 16)
                accum = ((buf[0] << 8) + buf[1]) >> (16 - off);
        else if(off <= 24)
                accum = ((buf[0] << 16) + (buf[1] << 8) + buf[2]) >> (24 - off);
        else if(off <= 31)
                accum = ((buf[0] << 24) + (buf[1] << 16)
                        + (buf[2] << 8) + (buf[3])) >> (32 - off);
        else if(nbits <= 31) {
                asn_per_data_t tpd = *pd;
                /* Here are we with our 31-bits limit plus 1..7 bits offset. */
                per_get_undo(&tpd, nbits);
                /* The number of available bits in the stream allow
                 * for the following operations to take place without
                 * invoking the ->refill() function */
                accum  = per_get_few_bits(&tpd, nbits - 24) << 24;
                accum |= per_get_few_bits(&tpd, 24);
        } else {
                per_get_undo(pd, nbits);
                return -1;
        }

        accum &= (((uint32_t)1 << nbits) - 1);

        ASN_DEBUG("  [PER got %2d<=%2d bits => span %d %+ld[%d..%d]:%02x (%d) => 0x%x]",
                (int)nbits, (int)nleft,
                (int)pd->moved,
                (((long)pd->buffer) & 0xf),
                (int)pd->nboff, (int)pd->nbits,
                ((pd->buffer != NULL)?pd->buffer[0]:0),
                (int)(pd->nbits - pd->nboff),
                (int)accum);

        return accum;
}

/*
 * Extract a large number of bits from the specified PER data pointer.
 */
int
per_get_many_bits(asn_per_data_t *pd, uint8_t *dst, int alright, int nbits) {
        int32_t value;

        if(alright && (nbits & 7)) {
                /* Perform right alignment of a first few bits */
                value = per_get_few_bits(pd, nbits & 0x07);
                if(value < 0) return -1;
                *dst++ = value; /* value is already right-aligned */
                nbits &= ~7;
        }

        while(nbits) {
                if(nbits >= 24) {
                        value = per_get_few_bits(pd, 24);
                        if(value < 0) return -1;
                        *(dst++) = value >> 16;
                        *(dst++) = value >> 8;
                        *(dst++) = value;
                        nbits -= 24;
                } else {
                        value = per_get_few_bits(pd, nbits);
                        if(value < 0) return -1;
                        if(nbits & 7) { /* implies left alignment */
                                value <<= 8 - (nbits & 7),
                                nbits += 8 - (nbits & 7);
                                if(nbits > 24)
                                        *dst++ = value >> 24;
                        }
                        if(nbits > 16)
                                *dst++ = value >> 16;
                        if(nbits > 8)
                                *dst++ = value >> 8;
                        *dst++ = value;
                        break;
                }
        }

        return 0;
}

/*
 * X.691-201508 #10.9 General rules for encoding a length determinant.
 * Get the optionally constrained length "n" from the stream.
 */
ssize_t
uper_get_length(asn_per_data_t *pd, int ebits, int *repeat) {
    ssize_t value;

    *repeat = 0;

    /* #11.9.4.1 Encoding if constrained (according to effective bits) */
    if(ebits >= 0 && ebits <= 16) {
        return per_get_few_bits(pd, ebits);
    }

        value = per_get_few_bits(pd, 8);
    if((value & 0x80) == 0) { /* #11.9.3.6 */
        return (value & 0x7F);
    } else if((value & 0x40) == 0) { /* #11.9.3.7 */
        /* bit 8 ... set to 1 and bit 7 ... set to zero */
        value = ((value & 0x3f) << 8) | per_get_few_bits(pd, 8);
        return value; /* potential -1 from per_get_few_bits passes through. */
    } else if(value < 0) {
        return -1;
    }
    value &= 0x3f; /* this is "m" from X.691, #11.9.3.8 */
    if(value < 1 || value > 4) {
        return -1; /* Prohibited by #11.9.3.8 */
    }
    *repeat = 1;
    return (16384 * value);
}

/*
 * Get the normally small length "n".
 * This procedure used to decode length of extensions bit-maps
 * for SET and SEQUENCE types.
 */
ssize_t
uper_get_nslength(asn_per_data_t *pd) {
        ssize_t length;

        ASN_DEBUG("Getting normally small length");

        if(per_get_few_bits(pd, 1) == 0) {
                length = per_get_few_bits(pd, 6) + 1;
                if(length <= 0) return -1;
                ASN_DEBUG("l=%d", (int)length);
                return length;
        } else {
                int repeat;
                length = uper_get_length(pd, -1, &repeat);
                if(length >= 0 && !repeat) return length;
                return -1; /* Error, or do not support >16K extensions */
        }
}

/*
 * Get the normally small non-negative whole number.
 * X.691, #10.6
 */
ssize_t
uper_get_nsnnwn(asn_per_data_t *pd) {
        ssize_t value;

        value = per_get_few_bits(pd, 7);
        if(value & 64) {        /* implicit (value < 0) */
                value &= 63;
                value <<= 2;
                value |= per_get_few_bits(pd, 2);
                if(value & 128) /* implicit (value < 0) */
                        return -1;
                if(value == 0)
                        return 0;
                if(value >= 3)
                        return -1;
                value = per_get_few_bits(pd, 8 * value);
                return value;
        }

        return value;
}

/*
 * X.691-11/2008, #11.6
 * Encoding of a normally small non-negative whole number
 */
int
uper_put_nsnnwn(asn_per_outp_t *po, int n) {
        int bytes;

        if(n <= 63) {
                if(n < 0) return -1;
                return per_put_few_bits(po, n, 7);
        }
        if(n < 256)
                bytes = 1;
        else if(n < 65536)
                bytes = 2;
        else if(n < 256 * 65536)
                bytes = 3;
        else
                return -1;      /* This is not a "normally small" value */
        if(per_put_few_bits(po, bytes, 8))
                return -1;

        return per_put_few_bits(po, n, 8 * bytes);
}


/* X.691-2008/11, #11.5.6 -> #11.3 */
int uper_get_constrained_whole_number(asn_per_data_t *pd, unsigned long *out_value, int nbits) {
        unsigned long lhalf;    /* Lower half of the number*/
        long half;

        if(nbits <= 31) {
                half = per_get_few_bits(pd, nbits);
                if(half < 0) return -1;
                *out_value = half;
                return 0;
        }

        if((size_t)nbits > 8 * sizeof(*out_value))
                return -1;  /* RANGE */

        half = per_get_few_bits(pd, 31);
        if(half < 0) return -1;

        if(uper_get_constrained_whole_number(pd, &lhalf, nbits - 31))
                return -1;

        *out_value = ((unsigned long)half << (nbits - 31)) | lhalf;
        return 0;
}


/* X.691-2008/11, #11.5.6 -> #11.3 */
int uper_put_constrained_whole_number_s(asn_per_outp_t *po, long v, int nbits) {
        /*
         * Assume signed number can be safely coerced into
         * unsigned of the same range.
         * The following testing code will likely be optimized out
         * by compiler if it is true.
         */
        unsigned long uvalue1 = ULONG_MAX;
                 long svalue  = uvalue1;
        unsigned long uvalue2 = svalue;
        assert(uvalue1 == uvalue2);
        return uper_put_constrained_whole_number_u(po, v, nbits);
}

int uper_put_constrained_whole_number_u(asn_per_outp_t *po, unsigned long v, int nbits) {
        if(nbits <= 31) {
                return per_put_few_bits(po, v, nbits);
        } else {
                /* Put higher portion first, followed by lower 31-bit */
                if(uper_put_constrained_whole_number_u(po, v >> 31, nbits - 31))
                        return -1;
                return per_put_few_bits(po, v, 31);
        }
}

int
per_put_aligned_flush(asn_per_outp_t *po) {
    uint32_t unused_bits = (0x7 & (8 - (po->nboff & 0x07)));
    size_t complete_bytes =
        (po->buffer ? po->buffer - po->tmpspace : 0) + ((po->nboff + 7) >> 3);

    if(unused_bits) {
        po->buffer[po->nboff >> 3] &= ~0 << unused_bits;
    }

    if(po->outper(po->tmpspace, complete_bytes, po->op_key) < 0) {
        return -1;
    } else {
        po->buffer = po->tmpspace;
        po->nboff = 0;
        po->nbits = 8 * sizeof(po->tmpspace);
        po->flushed_bytes += complete_bytes;
        return 0;
    }
}

/*
 * Put a small number of bits (<= 31).
 */
int
per_put_few_bits(asn_per_outp_t *po, uint32_t bits, int obits) {
        size_t off;     /* Next after last bit offset */
        size_t omsk;    /* Existing last byte meaningful bits mask */
        uint8_t *buf;

        if(obits <= 0 || obits >= 32) return obits ? -1 : 0;

        ASN_DEBUG("[PER put %d bits %x to %p+%d bits]",
                        obits, (int)bits, po->buffer, (int)po->nboff);

        /*
         * Normalize position indicator.
         */
        if(po->nboff >= 8) {
                po->buffer += (po->nboff >> 3);
                po->nbits  -= (po->nboff & ~0x07);
                po->nboff  &= 0x07;
        }

        /*
         * Flush whole-bytes output, if necessary.
         */
        if(po->nboff + obits > po->nbits) {
                size_t complete_bytes;
                if(!po->buffer) po->buffer = po->tmpspace;
                complete_bytes = (po->buffer - po->tmpspace);
                ASN_DEBUG("[PER output %ld complete + %ld]",
                        (long)complete_bytes, (long)po->flushed_bytes);
                if(po->outper(po->tmpspace, complete_bytes, po->op_key) < 0)
                        return -1;
                if(po->nboff)
                        po->tmpspace[0] = po->buffer[0];
                po->buffer = po->tmpspace;
                po->nbits = 8 * sizeof(po->tmpspace);
                po->flushed_bytes += complete_bytes;
        }

        /*
         * Now, due to sizeof(tmpspace), we are guaranteed large enough space.
         */
        buf = po->buffer;
        omsk = ~((1 << (8 - po->nboff)) - 1);
        off = (po->nboff + obits);

        /* Clear data of debris before meaningful bits */
        bits &= (((uint32_t)1 << obits) - 1);

        ASN_DEBUG("[PER out %d %u/%x (t=%d,o=%d) %x&%x=%x]", obits,
                (int)bits, (int)bits,
                (int)po->nboff, (int)off,
                buf[0], (int)(omsk&0xff),
                (int)(buf[0] & omsk));

        if(off <= 8)    /* Completely within 1 byte */
                po->nboff = off,
                bits <<= (8 - off),
                buf[0] = (buf[0] & omsk) | bits;
        else if(off <= 16)
                po->nboff = off,
                bits <<= (16 - off),
                buf[0] = (buf[0] & omsk) | (bits >> 8),
                buf[1] = bits;
        else if(off <= 24)
                po->nboff = off,
                bits <<= (24 - off),
                buf[0] = (buf[0] & omsk) | (bits >> 16),
                buf[1] = bits >> 8,
                buf[2] = bits;
        else if(off <= 31)
                po->nboff = off,
                bits <<= (32 - off),
                buf[0] = (buf[0] & omsk) | (bits >> 24),
                buf[1] = bits >> 16,
                buf[2] = bits >> 8,
                buf[3] = bits;
        else {
                if(per_put_few_bits(po, bits >> (obits - 24), 24)) return -1;
                if(per_put_few_bits(po, bits, obits - 24)) return -1;
        }

        ASN_DEBUG("[PER out %u/%x => %02x buf+%ld]",
                (int)bits, (int)bits, buf[0],
                (long)(po->buffer - po->tmpspace));

        return 0;
}


/*
 * Output a large number of bits.
 */
int
per_put_many_bits(asn_per_outp_t *po, const uint8_t *src, int nbits) {

        while(nbits) {
                uint32_t value;

                if(nbits >= 24) {
                        value = (src[0] << 16) | (src[1] << 8) | src[2];
                        src += 3;
                        nbits -= 24;
                        if(per_put_few_bits(po, value, 24))
                                return -1;
                } else {
                        value = src[0];
                        if(nbits > 8)
                                value = (value << 8) | src[1];
                        if(nbits > 16)
                                value = (value << 8) | src[2];
                        if(nbits & 0x07)
                                value >>= (8 - (nbits & 0x07));
                        if(per_put_few_bits(po, value, nbits))
                                return -1;
                        break;
                }
        }

        return 0;
}

/*
 * Put the length "n" (or part of it) into the stream.
 */
ssize_t
uper_put_length(asn_per_outp_t *po, size_t length) {

        if(length <= 127)       /* #10.9.3.6 */
                return per_put_few_bits(po, length, 8)
                        ? -1 : (ssize_t)length;
        else if(length < 16384) /* #10.9.3.7 */
                return per_put_few_bits(po, length|0x8000, 16)
                        ? -1 : (ssize_t)length;

        length >>= 14;
        if(length > 4) length = 4;

        return per_put_few_bits(po, 0xC0 | length, 8)
                        ? -1 : (ssize_t)(length << 14);
}


/*
 * Put the normally small length "n" into the stream.
 * This procedure used to encode length of extensions bit-maps
 * for SET and SEQUENCE types.
 */
int
uper_put_nslength(asn_per_outp_t *po, size_t length) {

        if(length <= 64) {
                /* #10.9.3.4 */
                if(length == 0) return -1;
                return per_put_few_bits(po, length-1, 7) ? -1 : 0;
        } else {
                if(uper_put_length(po, length) != (ssize_t)length) {
                        /* This might happen in case of >16K extensions */
                        return -1;
                }
        }

        return 0;
}
